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प्रश्न
Answer the following in detail.
Define friction and explain how it is useful to us.
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उत्तर
Friction is a force that opposes relative motion between two bodies/surfaces in contact with each other. Although friction opposes the motion, it also makes motion possible.
Friction helps us do many things like :
- It helps us in walking. In the absence of friction, we may slip or M.
- Cars and buses are able to move safely on roads due to the friction between the treaded tires of these vehicles and the surface of the road.
- Friction allows us to hold objects with our hands.
- It allows us to write on paper.
- Friction produces heat. In winter, when we rub our cold hands, the heat produced due to friction makes our hands warm.
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संबंधित प्रश्न
Suppose your writing desk is tilted a little. A book kept on it starts sliding down. Show the direction of frictional force acting on it.
When a glass rod is rubbed with a piece of silk cloth the rod ______.
A charged glass rod attracts a charged plastic straw.
Name the three kinds of friction.
Define static friction
Fill in the blank.
More the roughness of a surface, greater is the ........................
Tick the most appropriate answer.
Friction produces
Answer the following in short.
How can sliding friction be changed into rolling friction easily?
Match the following.
| Column I | Column II | |
| a) | Static friction | viscosity |
| b) | Kinetic friction | least friction |
| c) | Rolling friction | objects are in motion |
| d) | Friction between the liquid layers | objects are sliding |
| e) | Sliding friction | objects are at rest |
Complete the analogy.
Knot in a thread : _____ friction : : Ball bearing : _____ friction
